I love deviant art and google. Usually, if I can't find what I'm looking for on deviant art, Google is your friend. Usually for my own characters, I tend to go cute/pretty. With the Monsters, it broadens my horizons.

I figured that with the description on the Sea Hag, their true form should be nightmare fuel. That one fit the bill.

Harpies are entirely self-serving bird-women, who use their hypnotic song and beauty to lead their prey to unspeakable horrors and tortures, only to kill them and eat them when they get bored with their 'play'.

One of the most famous of the classic monsters, the Hydra multiplies your problems by two, every time you try to behead it unless you sear it with fire or acid. Some rare varieties also have a cone of cold or cone of fire breath weapon to add insult to injury. Or just add more injuries. There's a moral there somewhere.

Inevitables are intelligent, celestial clockwork droids whose sole purpose is to bring justice to those who break the natural laws of the universe. They come in many different sizes and types, though they all share similar characteristics.
For example: Kolyaruts punish oath-breakers, Maruts punish those who cheat death by unnatural means, Zelekhuts hunt those who deny justice or try to escape justice.